The invention relates to a miter saw and in particular to a bearing arrangement for supporting a turntable on the base of a miter saw.
Miter saws, typically include a base having a support surface for supporting a workpiece, and a turntable connected to the base for pivotal movement about a vertical axis. The turntable typically includes a workpiece support surface forming with the support surface of the base a smooth continuous upper surface and further includes a saw arm mounted on the turntable for movement with the turntable about the vertical axis. The turntable also includes a central opening, and a kerf plate is bolted onto the turntable in the central opening to provide additional support to the workpiece during cutting of the workpiece.
The saw arm is connected to the turntable for pivotal movement about a first horizontal axis between a raised position and a cutting position. In a compound miter saw, the saw arm is also connected to the turntable for movement about a second horizontal or bevel angle axis to allow the user of the saw to make angular bevel cuts in the workpiece. Movement of the saw arm between the non-cutting and cutting positions and about the bevel angle axis creates a moment force on the turntable about the vertical axis of the turntable. In order to provide adequate support for the workpiece, it is important that the turntable be stable during the cutting operation. Repetitive pivotal movement of the turntable about the vertical axis causes wear of the engaging surfaces between the base and the turntable. Wear can result in the development of a loose fit between the base and the turntable. The loose fit allows rocking movement of the turntable with respect to the base and in response to the moment force on the turntable. Rocking movement of the turntable reduces the accuracy and reliability of the miter saw.
The invention provides a cutting tool or miter saw including a base having a support surface for supporting a workpiece. A turntable is supported by the base for rotation about a generally vertical axis. The turntable includes a support surface which forms a smooth continuous workpiece supporting surface with the support surface of the base and the turntable has an aperture in the workpiece support surface. A cutting miter saw arm is supported by the turntable for pivotal movement with the turntable about the vertical axis and for pivotal movement about a first horizontal axis between a raised position and a cutting position and about a bevel angle axis to allow compound miter cutting of a workpiece. The base includes a recess for housing the turntable, and a circular bearing in the recess.
The circular bearing is mounted between the turntable and the base, has a generally horizontal support surface, and is mounted on the base to support the turntable on the base. The bearing also includes a bearing cage which houses a plurality of bearing elements. The provision of a bearing assembly between the bearing surfaces of the turntable and the base substantially eliminates the wear on the bearing surfaces and provides support to the turntable. Also, the provision of a bearing including a generally horizontal support which is spaced radially from the vertical axis provides greater stability against rocking movement of the turntable relative to the base.
The miter saw also includes a biasing means for biasing the turntable toward the base. The provision of a biasing mechanism to bias the turntable toward the base provides added stability to the turntable to maintain the smooth, uninterrupted and continuous upper surface formed by the respective support surfaces of the turntable and the base. The provision of a smooth continuous upper surface is necessary in order to precisely cut a workpiece at a desired position.
The miter saw also includes a kerf plate which is housed within and which covers the aperture in the turntable. The kerf plate includes one end having a guide member which extends into the guide slot on the turntable and an opposite end having a pair of snap-fit latch members extending into the snapfit recesses in the turntable. The snap-fit latch members are selectively engageable to allow quick and easy insertion and removal of the kerf plate from the turntable.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.